Catalyst for Selective Dehydrogenation / Oxidative Dehydrogenation Reactions and Process for the Preparation Thereof

ABSTRACT

The present invention provides a process and catalyst for the direct and selective conversion of ethane to ethylene. The process provides a direct single step vapor phase selective dehydrogenation/oxidative dehydrogenation of ethane to ethylene over Mo supported nanocrystalline TiO 2 . The process provides ethane conversion of 65-96% and selectivity of ethylene up to 100%. The process may be conducted in the presence or absence of oxygen.

The following specification particularly describes the invention and themanner in which it is to be performed:

CROSS-REFERENCE TO EARLIER-FILED APPLICATIONS

The present application claims the benefit of Indian application No.3443/DEL/2012 filed Nov. 7, 2012, the entire disclosure of which ishereby incorporated by reference.

FIELD OF THE INVENTION

The present invention related to catalyst for the selectivedehydrogenation/oxidative dehydrogenation of ethane to ethylene.Particularly the present invention relates to a catalyst for the vaporphase dehydrogenation/oxidative dehydrogenation of ethane to ethyleneunder atmospheric pressure. More particularly, the present inventionrelates to a process future to produce ethylene from ethane with highconversion and selectivity in one single step. The present inventionrelates to an improved process for the preparation of Mo supportednanocrystalline TiO₂; the catalyst can effectively produce ethylenewithout any deactivation in a longer run.

BACKGROUND OF THE INVENTION

Ethylene is a very important chemical, which does not occur in naturebut still represents the organic chemicals consumed in the greaterquantity worldwide. It is mainly the raw material for a large no ofindustrial products, such as poly-ethylene, polyvinyl chloride,polystyrene, polyester etc. Despite of the economic uncertainty aroundthe petrochemical industry, ethylene production and consumption scenarioare expected to grow continuously. The global demand of ethylene is over140 million tons per year with the future growth rate of 3.5% per year(www.technip.com/sites/default/files/technip/publications/attachments/-Ethylene_production_(—)1.pdf).Industrially, ethylene is produced by steam cracking of ethane; reactorshave to plug into a firebox as the cracking of ethane is endothermic innature. In standard condition a steam cracker can achieve up to 60% ofethane conversion with maximum 80% ethylene selectivity. However,oxidative dehydrogenation (ODH) is one of the alternative processesmainly known. Since, oxidative dehydrogenation is exothermic so thereaction goes automatically as the catalyst is light off. While, ODH canoffers high conversion with high ethylene selectivity, minimizing thecontact time in milliseconds.

In this context, oxidative dehydrogenation (ODH) will have the clearfuture to replace steam cracker to produce ethylene. Although manyresearcher has reported oxidative dehydrogenation of ethane in resentpast, but poor atom efficiency (called E-factor by R A Sheldon inChemistry & Industry, 6 Jan. 1997, P 13) in respect to both conversionand selectivity restrict the successful commercialization of ODHprocess. Moreover, the use of pure oxygen in ODH process makes theprocess cost high; hence to deploy ODH reactor industry must put acostly gas separation tower first. In this context catalyticdehydrogenation is another possibility to replace the existing processesof ethylene production, as it can deliver ≧80% ethane conversion with≧90% ethylene conversion. Uses of solid nanocrystalline metal oxidescatalyst are very important as they offer larger active surface areawith option to reuse.

There are many reports on the dehydration as well as oxidativedehydrogenation (ODH) of ethane over different solid catalyst, but tothe best of our knowledge there is no reference available that can offersuch atom efficiency for a prolonged reaction time.

Reference can be made to European patent EP 2165997 A1, 2010 wherein Hanet al. provided a novel one step catalytic process of oxidativedehydrogenation of ethane for the production of ethylene and carbondioxide using pure oxygen over Fe-manganese oxide or Fe—CaCO₃ catalyst.But use of pure oxygen at a temperature≧600° C. is very much painful,because above 600° C., thermal cracking will come into effect. So use ofpure oxygen at above 600° C. makes the process cost higher andunfavourable for commercialization.

Reference can be made to U.S. Pat. No. 4,250,346, 1981 by Young et al.In their patent application, they claimed gas phase oxidativedehydrogenation of ethane in presence or absence of H₂O₂ overmix-Molybdenum oxide catalyst (Mo_(a) X_(b) Y_(c)) (where X=Cr, Mn, Nb,Ta, Ti, V, W and Y=Bi, Ce, Co, Cu, Fe, Mg, K, Ni, P etc.) at ≦500° C.The drawbacks of this process are the low conversion of butane (only 2to 8% of ethane conversion was claimed) although the process operates at1-30 atmosphere pressure. Again, the use of H₂O rise the question ofmetal leaching from the solid catalyst, leads to rapid deactivation ofcatalyst.

Reference can be made to the article AIChE journal, 1997, 43, 1545-1550in which Choudhary et al. studied non-catalytic thermal cracking ofethane in presence of oxygen in a space velocity of 2000-11000 h⁻¹. But,the conversion of ethane is only 44.2% whereas in absence of oxygen isfurther decreases to 28.5%. Moreover, the selectivity of ethylene goesdown as the side reaction product (such as CH₄, C₃H₆, C₃H₈ etc.) arepredominates at 800° C.

Reference can be made to the U.S. Pat. No. 4,524,236 by McCain et al. inwhich they developed one step low temperature oxidative dehydrogenationof ethane to produce ethylene over mixed oxide catalyst with 1: 1.2oxygen to ethane as feed. The main drawback of the process is the lowspace velocity, loss of selectivity (about 11% selectivity decreased asthe conversion goes up from 53% to 76%). The low space velocity makesthe industrial difficult, as the industry need process which can givesteady conversion and selectivity in a high space velocity in order tocut down the production cost.

Reference can be made to the J. Catal., 2010, 270, 67-75 whereinLemoniou et al. reported low temperature oxidative dehydrogenation ofethane to ethylene over Ni—Me—O (where Me is the doped metal) ascatalyst. Under the reported process 46% ethylene yield at 400° C. hasbeen achieved with Ni—Nb—O catalyst.

Reference may also be made to Chem. Comm., 2003, 18, 2294-2295, in whichpartial oxidation of ethane was carried out via bromination followed byreaction with mix metal oxide. A product selectivity of ≧80% wasachieved over Co₂O₄:ZrO₂ catalyst. But main drawback is the use ofbromine and double stage reactor setup to achieve such high productselectivity.

Another reference can be made to Ind. Eng. Chem. Res., 2011, 50,8438-8442, by Leclerc et al. on the ODH of ethane over platinumcatalyst. Wherein, silica supported platinum catalyst demonstrate thehighest conversion of 76% with ethylene yield of 46% at 900° C. withC₂H₆/O₂ ratio of 1.5.

OBJECTS FOR THE INVENTION

Main object of the present invention is to provide a catalyst for theselective dehydrogenation/oxidative dehydrogenation of ethane toethylene.

Another object of the present invention is to provide an improvedprocess for the preparation of catalyst for the selectivedehydrogenation/oxidative dehydrogenation of ethane to ethylene.

Yet another object of the present invention is to provide a process forthe vapor phase dehydrogenation/oxidative dehydrogenation of ethane toethylene under atmospheric pressure.

Yet another object of the present invention is to provide a processfuture to produce ethylene from ethane with high conversion andselectivity in one single step.

Yet another object of the present invention is to provide an efficientMo supported nanocrystalline TiO₂; the catalyst can effectively produceethylene without any deactivation in a longer run.

SUMMARY OF THE INVENTION

Accordingly, present invention provides Mo—TiO₂ nanocrystalline oxidecatalyst wherein Mo is in the range of 5 to 15 wt % and TiO₂ in therange of 85 to 95 wt % having particle size in the range of 80-150 nm.

In an embodiment of the present invention, Mo—Ti_(O2) nanocrystallineoxide catalyst as claimed in claim 1, wherein said catalyst is usefulfor production of ethylene from ethane by vapor phasedehydrogenation/oxidative dehydrogenation in absence and presence ofoxygen.

In an embodiment, present invention provides a process for thepreparation of Mo—TiO₂ nanocrystalline oxide catalyst as used in claim 1and the said process comprising the steps of:

-   -   i. mixing titanium isopropoxide Ti(i-Pr)₄, ethanol and        octadecyldimethyl (3-trimethoxy silylpropyl) ammonium chloride        in the ratio ranging between 50:3500:1 to 100:3500:1 followed by        adjusting pH between 3-10 to obtain mixed solution;    -   ii. heating mixed solution as obtained in step (i) at        temperature in the range of 70 to 90° C. for period in the range        of 1 to 2 h;    -   iii. autoclaving the solution as obtained in step (ii) at a        temperature in the range of 150 to 200° C. hydrothermally for        period in the range of 20 to 30 h;    -   iv. filtering, washing and drying the autoclaved solution as        obtained in step (iii) at a temperature in the range of 100 to        130° C. for period in the range of 10 to 18 h;    -   v. calcining the materials as obtained in step (iv) at        temperature in the range of 300 to 800° C. for period in the        range of 4 to 6 h in air to yield solid TiO₂;    -   vi. mixing MoCl₃, cetyltrimethylammonium bromide and hydrazine        in the molar ratio of Mo, CTAB and Hydrazine ranging between        1:1:0.01 to 1:2:0.01 followed by adding TiO2 as obtained in        step (v) maintaining weight ratio of Mo to TiO₂ in the range of        0.05 to 0.15;    -   vii. stirring the mixture as obtained in step (vi) for period in        the range of 2 to 5 h, filtering followed by drying the        materials in oven at a temperature ranging between 100 to        130° C. for period in the range of 10 to 18 h;    -   viii. calcining the material at temperature in the range of 300        to 800° C. for period in the range of 4 to 6 h in air to yield        Mo—TiO₂ nanocrystalline oxide catalyst.

In another embodiment, present invention provides a process for theproduction of ethylene from ethane by vapor phasedehydrogenation/oxidative dehydrogenation in absence and presence ofoxygen using Mo—TiO₂ nanocrystalline oxide catalyst and the said processcomprising the steps of:

-   -   i. passing ethane at atmospheric pressure, at a temperature        range of 550-850° C. with a gas hourly space velocity (GHSV) in        the range of 5000-70000 ml g⁻¹ h⁻¹ in the presence or absence of        molecular oxygen as feed and helium as carrier over Mo supported        TiO₂ catalyst with Mo to TiO₂ weight ratio varied between 0.03        to 0.2 for a period of 1-20 hours to obtain desired product        ethylene.

In yet another embodiment of the present invention, reaction temperatureis preferably in the range 650 to 800° C.

In yet another embodiment of the present invention, gas hourly spacevelocity (GHSV) is preferably in the range of 10000 to 50000 ml g⁻¹ h⁻¹.

In yet another embodiment of the present invention, the reaction timeused is preferably in the range 3 to 20 h.

In yet another embodiment of the present invention, the conversionpercentage of ethane is in the range of 65 to 96 mol %.

In yet another embodiment of the present invention, the selectivity ofthe ethylene obtained in the range of 88 to 100 mol %.

BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 represents the conversion of ethane to ethylene over time onstream for the Mo—TiO₂ catalyst.

FIG. 2 represents X-ray Diffraction (XRD) pattern of the preparedcatalyst.

FIG. 3 represents Scanning Electron Microscope (SEM) images of theprepared Mo—TiO2 catalysts.

FIG. 4 represents Transmission Electron Microscope (TEM) images of theprepared catalyst.

DETAILED DESCRIPTION OF THE INVENTION

Present invention provides a catalyst consisting of Mo—TiO₂ preparedhydrothermally and process to produce ethylene from ethane by gas phasedehydrogenation/oxidative dehydrogenation with and without O₂ overMo—TiO₂ catalyst at atmospheric pressure, at a temperature range of 550to 850° C. with a gas hourly space velocity (GHSV) in the range of5000-70000 ml g⁻¹ h⁻¹ in the presence of Mo supported TiO₂ catalyst withMo to TiO₂ weight ratio varied between 0.03 to 0.2 to obtain desiredproduct ethylene for a period of 1-20 hours.

The present invention provides a process for the production of ethylenefrom ethane by vapor phase dehydrogenation/oxidative dehydrogenation inabsence and presence of oxygen and Mo—TiO₂ nanocrystalline oxide as thecatalyst which involves the following steps:

-   -   i. Synthesis of TiO₂ oxide using sol composition of Ti(i-Pr)₄,        octadecyldimethyl (3-trimethoxy silylpropyl) ammonium chloride,        1N NaOH solution to adjust the pH between 3-10;    -   ii. heated at 80° C. and maintained for 1-2 h;    -   iii. Transferring the solution into an closed Teflon line        stainless steel autoclave and heating the solution inside the        oven in the temperature range between 150-200° C. hydrothermally        for 20-30 h;    -   iv. filtered the material by washing with excess water (2 litre)        followed by drying the materials in oven at a temperature        between 100-130° C. for 10-18 h;    -   v. Calcination of the materials at 300-800° C. for 4-6 h in air        to yield solid TiO2;    -   vi. Synthesis of Mo—TiO₂ catalyst using ethanol medium taking        the solution composition of MoCl₃, cetyltrimethylammonium        hydrazine, in the molar ratio of Mo:CTAB:Hydrazine=1:1:0.01 and        prepared TiO₂;    -   vii. The weight ratio of Mo to TiO₂ varied in the range of 0.05        to 0.15;    -   viii. Stirring the mixture for 2-5 h followed and filtered the        material by washing with excess water (2 litre) followed by        drying the materials in oven at a temperature between        100-130° C. for 10-18 h;    -   ix. Calcination of the materials at 300-800° C. for 4-6 h in air        to yield Mo—TiO2;    -   x. Dehydrogenation/oxidative dehydrogenation of ethane was        carried out in a fixed bed down-flow reactor using ultra-pure        ethane and/or molecular oxygen as feeds and helium as carrier        for 1-20 h to yield ethylene;    -   xi. The process pressure was kept at 1 atmosphere;    -   xii. The reaction temperature is preferably in the range 650 to        800° C.;    -   xiii. The gas hourly space velocity (GHSV in ml g⁻¹ h⁻¹) is        preferably in the range 10000 ml g−1 h−1 to 50000 ml g−1 h−1;    -   xiv. The ethane conversion (mol %) of 65-96% is obtained and        selectivity (mol %) to ethylene is 78 to 100%.

The detailed steps of the process are:

The dehydrogenation of ethane was carried out in a fixed-bed down flowreactor at atmospheric pressure. Typically 200 mg of catalyst was placedin between two quartz wool plugged in the centre of the 6 mm quartzreactor and dehydrogenation of ethane was carried out in a temperaturerange of 650-800° C. The catalyst was reduced using 5% H₂ balance He at650° C. for 1 h before the reaction. The gas hourly space velocity(GHSV) was varied between 5000 ml g⁻¹ h⁻¹ to 50000 ml g⁻¹ h⁻¹ with amolar ratio of C₂H₆:O₂:He of 1:1:8. The reaction products were analyzedusing an online gas chromatography (Agilent 7890A) fitted with a FID &TCD detector using Al₂O₃/KCl column (to analyse C₂H₆, C₂H₄, CH₄ etc.)and PoraPack-Q (for analyzing O₂ and CO₂).

An improved process for the preparation of Mo—TiO2 catalyst, wherein thesaid process comprising the steps of:

-   -   a) Mixing the chemicals: Ti(i-Pr)₄, octadecyldimethyl        (3-trimethoxy silylpropyl) ammonium chloride and 1N NaOH        solution to adjust the pH between 3-10.    -   b) Heating the solution at 80° C. and maintained for 1-2 h    -   c) Transferring the solution into a closed Teflon line stainless        steel autoclave and heating the solution inside the oven in the        temperature range between 150-200° C. hydrothermally for 20-30        h.    -   d) filtered the material by washing with excess water (2 litre)        followed by drying the materials in oven at a temperature        between 100-130° C. for 10-18 h    -   e) Calcination of the materials at 300-800° C. for 4-6 h in air        to yield solid TiO₂.    -   f) Synthesis of Mo—TiO₂ catalyst using ethanol medium taking the        solution composition of MoCl₃ cetyltrimethylammonium bromide,        hydrazine, in the molar ratio of Mo:CTAB:Hydrazine=1:1:0.01 and        prepared TiO₂    -   g) The weight ratio of Mo to TiO₂ varied in the range of 0.05 to        0.15    -   h) Stirring the mixture for 2-5 h followed and filtered the        material by washing with excess water (2 litre) followed by        drying the materials in oven at a temperature between        100-130° C. for 10-18 h    -   i) Calcination of the materials at 300-800° C. for 4-6 h in air        to yield Mo—TiO₂

A process for gas phase dehydrogenation/oxidative dehydrogenation withand without O₂ of ethane to produce ethylene using catalyst comprisingthe steps of:

-   -   I. Passing ethane at atmospheric pressure, at a temperature        range of 550-850° C. with a gas hourly space velocity (GHSV) in        the range of 5000-70000 ml g⁻¹ h⁻¹ in the presence of Mo        supported TiO₂ catalyst with Mo to TiO₂ weight ratio varied        between 0.03 to 0.2 to obtain desired product ethylene for a        period of 1-20 hours.

Weight ratio of Mo to TiO₂ of the catalyst varied in the range of 0.05to 0.15.

Reactor pressure is preferably in the range of 1 atmosphere. Reactiontemperature is preferably in the range 650 to 800° C. Gas hourly spacevelocity (GHSV) is preferably in the range of 1000 g ml⁻¹ h⁻¹ to 50000 gml⁻¹ h⁻¹. Reaction time used is preferably in the range 3-20 h.Conversion (mol %) of ethane is in the range of 65 to 96%. Selectivity(mol %) of the ethylene obtained in the range of 78 to 100%.

EXAMPLES

The following examples are given by way of illustration and thereforeshould not be construed to limit the scope of the invention.

Example 1 Synthesis of TiO₂

5 ml titanium isopropoxide was taken in 75 ml chilled ethanol to form aheterogeneous solution. Approximately 0.2 g octadecyldimethyl(3-trimethoxy silylpropyl) ammonium chloride was added drop wise undervigorous stirring. Then, the pH of the mixed solution was adjusted by1(M) NaOH solution and pH of the mixed solution was fixed at 10.Finally, the mixed solution was heated at 80° C. and maintained for 2 h.The resultant mixture was autoclaved at 180° C. for 24 h for furthercrystallization. The white precipitate (TiO₂) was collected byfiltration, washed thoroughly with distilled water and ethanol and driedat 80° C. for 12 h. To remove the template the as-synthesized materialwas heated to 750° C. with a temperature ramp of 1.5° C./min understatic air and kept at the same temperature for 4 h. This was used as aTiO₂ support material.

Synthesis of Mo—TiO₂

Synthesis of Mo—TiO₂ catalyst using ethanol (25 ml) medium taking thesolution composition of 1.05 g of MoCl₃, 0.5 g of cetyltrimethylammoniumbromide, 0.2 g hydrazine (the molar ratio of Mo:CTAB:Hydrazine=1:1:0.01)and prepared 1.0 g of TiO₂ was added to it such a way that the weightratio of Mo to TiO₂ was 0.05. The mixture was stirred for 3 h and thesolid material was filtered out with 2 litre distilled water and it wasdried in the oven at 110° C. for 16 h. Finally the calcination of thematerial was carried out at 750° C. for 6 h in air.

The X-ray diffraction pattern, Scanning Electron Microscope (SEM) imagesand Transmission Electron Microscope (TEM) images of this material aregiven below.

Example 2

This example describes the dehydrogenation of ethane by gas phasereaction in He using Mo—TiO₂ nanocrystalline oxide as the catalyst.(Table-1)

The dehydrogenation of ethane to ethylene was carried out in a fixed-beddown flow quartz reactor at atmospheric pressure. Typically 200 mg ofcatalyst was placed in between two quartz wool plugged in the center ofthe 6 mm quartz reactor and dehydrogenation of ethane was carried out ina temperature range of 650-800° C. The gas hourly space velocity (GHSV)was varied between 10000 ml g⁻¹ h⁻¹ to 30000 ml g⁻¹ h⁻¹ with a molarratio of C₂H₆:He of 1:9.

Process Conditions

Catalyst: 0.2 g

Mo: TiO₂ wt % in the catalyst=5%Pressure: 1 atmosphereTotal flow=33.3 ml/min (GHSV=10000)Reaction time: 1 h

TABLE 1 Ethane Ethylene Catalyst Temperature Conversion SelectivityYield (5% Mo—TiO₂) (° C.) (mol %) (mol %) (%) Oxidative 750 91 84 76dehydrogenation (With O₂) dehydrogenation 750 86 95 82 (Without O₂)

Example—3

The example describes the effect of temperature on yield and selectivityethylene. The product analysis presented in Table-2.

Process Conditions:

Catalyst: 0.2 g

Mo: TiO₂ wt % in the catalyst=5%Pressure: 1 atmosphereTotal flow=33.3 ml/min (GHSV=10000)Reaction time: 1 h

TABLE 2 Effect of temperature on ethane conversion, ethylene yield andselectivity Ethane Ethylene Temperature Conversion Selectivity (molYield (° C.) (mol %) %) (%) Oxidative 650 65 89 58 dehydrogenation 70082 87 71 (With O₂) 750 91 84 76 800 96 78 74 dehydrogenation 650 10 10010 (Without 700 56 97 54 O₂) 750 86 95 82 800 94 89 84

Example—4

The example describes the effect of time on stream on yield andselectivity of ethylene. The product analysis presented in Table 3

Process Conditions:

Catalyst: 0.2 g, Mo: TiO₂ wt % in the catalyst=5%Pressure: 1 atmosphereTotal flow=33.3 ml/min (GHSV=10000)Reaction temperature: 750° C.

Example—5

The example describes the effect of gas hourly space velocity (GHSV) onyield and selectivity of ethylene. The product analysis presented inTable-3.

Process Conditions:

Catalyst: 0.2 g

Mo: TiO₂ wt % in the catalyst=5%Pressure: 1 atmosphereReaction temperature: 750° C.Reaction time: 1 h

TABLE 3 Effect of gas hourly space velocity (GHSV) on ethane conversion,ethylene yield and selectivity Ethane Ethylene GHSV ConversionSelectivity (mol Yield (ml g⁻¹ h⁻¹) (mol %) %) (%) Oxidative 10000 91 8476 dehydrogenation 15000 76 84 64 (With O₂) 20000 63 86 54 25000 54 8747 30000 48 89 43 dehydrogenation 10000 86 95 82 (Without 15000 79 96 76O₂) 20000 63 97 61 25000 52 98 51 30000 41 100 41

ADVANTAGES OF THE INVENTION

The main advantages of the present invention are:

-   -   1. The process of the present invention converts ethane to        ethylene in a single step with a single catalyst.    -   2. The process provides not only good conversion but also good        selectivity for ethylene.    -   3. The process produce nominal by-product in the form of methane        which is also a major advantage of this process.    -   4. The process does not need any addition reagent (such as        chlorine, bromine etc.) to generate active species.    -   5. The catalyst is used in very low amounts.    -   6. The catalyst does not deactivate till 20 h with the reaction        stream.

1. A Mo—TiO₂ nanocrystalline oxide catalyst wherein Mo is in the rangeof 5 to 15 wt % and TiO₂ in the range of 85 to 95 wt %, the catalysthaving particle size in the range of 80-150 nm.
 2. A Mo—TiO₂nanocrystalline oxide catalyst as claimed in claim 1, wherein saidcatalyst is useful for production of ethylene from ethane by vapor phasedehydrogenation/oxidative dehydrogenation in absence and presence ofoxygen.
 3. A process for the preparation of the Mo—TiO₂ nanocrystallineoxide catalyst of claim 1 wherein the process comprises the steps of: i.preparing TiO₂ as follows: a. mixing titanium isopropoxide Ti(i-Pr)₄,ethanol and octadecyldimethyl (3-trimethoxy silylpropyl) ammoniumchloride in the ratio ranging between 50:3500:1 to 100:3500:1 followedby adjusting the pH to between 3-10 to obtain a mixed solution; b.heating the mixed solution as obtained in step (a) at temperature in therange of 70 to 90° C. for a period in the range of 1 to 2 h; c.autoclaving the solution as obtained in step (b) at a temperature in therange of 150 to 200° C. hydrothermally for a period in the range of 20to 30 h to form a liquid containing solid material; d. separating thesolid material from step (c) by filtration, then washing the filteredsolid material, and then drying the washed solid material at atemperature in the range of 100 to 130° C. for a period in the range of10 to 18 h; e. calcining the materials as obtained in step (d) attemperature in the range of 300 to 800° C. for a period in the range of4 to 6 h in air to yield solid TiO₂; ii. mixing MoCl₃,cetyltrimethylammonium bromide and hydrazine at a molar ratio ofMo:CTAB:Hydrazine ranging from 1:1:0.01 to 1:2:0.01 followed by addingthe TiO₂ as obtained in step i. while maintaining the weight ratio of Moto TiO₂ in the range of 0.05 to 0.15 to form a mixture; iii. stirringthe mixture as obtained in step ii. for a period in the range of 2 to 5h, then filtering the mixture to form a solid material and then dryingthe solid material in an oven at a temperature ranging from 100 to 130°C. for a period in the range of 10 to 18 h; and iv. calcining thematerial of step iii. at a temperature in the range of 300 to 800° C.for a period in the range of 4 to 6 h in air to yield Mo—TiO₂nanocrystalline oxide catalyst.
 4. A process for the production ofethylene from ethane by vapor phase dehydrogenation/oxidativedehydrogenation, in absence or presence of oxygen, using Mo—TiO₂nanocrystalline oxide catalyst, the process comprising the steps of: i.passing ethane, at atmospheric pressure and at a temperature range of550-850° C. and a gas hourly space velocity (GHSV) in the range of5000-70000 ml g⁻¹ h⁻¹, with helium as carrier over Mo supported TiO₂catalyst, having a Mo to TiO₂ weight ratio ranging from 0.03 to 0.2, fora time period of 1-20 hours to obtain ethylene
 5. The process of claim4, wherein the reaction temperature is in the range 650 to 800° C. 6.The process of claim 4, wherein the gas hourly space velocity (GHSV) isin the range of 10000 to 50000 ml g⁻¹ h⁻¹.
 7. The process of claim 4,wherein the reaction time used is in the range 3 to 20 h.
 8. The processof claim 4, wherein the conversion percentage of ethane is in the rangeof 65 to 96 mol %.
 9. The process of claim 4, wherein the selectivity ofthe ethylene obtained in the range of 88 to 100 mol %.
 10. A process forthe preparation of Mo—TiO₂ nanocrystalline catalyst, the processcomprising: a. preparing solid TiO₂ from a mixture of titaniumisopropoxide Ti(i-Pr)₄ and octadecyldimethyl (3-trimethoxy silylpropyl)ammonium chloride, present in the ratio ranging from 50:3500:1 to100:3500:1, in liquid, wherein the mixture has been heated at atemperature in the range of 70 to 90° C. and then autoclaved at atemperature in the range of 150 to 200° C. to form a liquid containingsolid material, wherein the solid material is separated from the liquidand then calcined at a temperature in the range of 300 to 800° C. in airto yield the solid TiO₂.
 11. The process of claim 10 further comprising:a. mixing MoCl₃, cetyltrimethylammonium bromide and hydrazine, at amolar ratio of Mo:CTAB:hydrazine ranging from 1:1:0.01 to 1:2:0.01, in aliquid followed by adding the TiO₂, a weight ratio of Mo to TiO₂ in therange of 0.05 to 0.15, to form a mixture comprising a solid materialthat is separated and then calcined at a temperature in the range of 300to 800° C. in air to yield the Mo—TiO₂ nanocrystalline catalyst.
 12. Theprocess of claim 10 comprising: a. preparing solid TiO₂ from a mixtureof titanium isopropoxide Ti(i-Pr)₄ and octadecyldimethyl (3-trimethoxysilylpropyl) ammonium chloride, present in the ratio ranging from50:3500:1 to 100:3500:1, in liquid, wherein the mixture has been heatedat a temperature in the range of 70 to 90° C. and then autoclaved at atemperature in the range of 150 to 200° C. to form a liquid containingsolid material, wherein the solid material is separated from the liquidand the solid is dried at a temperature in the range of 100 to 130° C.,and then calcined at temperature in the range of 300 to 800° C. in airto yield the solid TiO₂.
 13. The process of claim 12 further comprising:a. mixing MoCl₃, cetyltrimethylammonium bromide and hydrazine, at amolar ratio of Mo:CTAB:hydrazine ranging from 1:1:0.01 to 1:2:0.01, in aliquid followed by adding the TiO₂, a weight ratio of Mo to TiO₂ in therange of 0.05 to 0.15, to form a mixture comprising a solid materialthat is separated and dried at a temperature ranging from 100 to 130° C.and calcined at a temperature in the range of 300 to 800° C. in air toyield the Mo—TiO₂ nanocrystalline oxide catalyst.
 14. The process ofclaim 10 comprising: a. preparing TiO₂ by: i. mixing titaniumisopropoxide Ti(i-Pr)₄ and octadecyldimethyl (3-trimethoxy silylpropyl)ammonium chloride, present in the ratio ranging from 50:3500:1 to100:3500:1, in a liquid and by adjusting the pH to between 3-10 toobtain a mixed solution; ii. heating the mixed solution at a temperaturein the range of 70 to 90° C. for a period in the range of 1 to 2 h; iii.autoclaving the solution as obtained in step ii. at a temperature in therange of 150 to 200° C. for a period in the range of 20 to 30 h to forma liquid containing solid material; iv. separating the solid material ofstep iii. from the liquid, then washing the separated solid material,and then drying the washed solid material at a temperature in the rangeof 100 to 130° C. for a period in the range of 10 to 18 h; v. calciningthe materials as obtained in step iv. at temperature in the range of 300to 800° C. for a period in the range of 4 to 6 h in air to yield solidTiO₂; b. mixing MoCl₃, cetyltrimethylammonium bromide and hydrazine, ata molar ratio of Mo:CTAB:hydrazine ranging from 1:1:0.01 to 1:2:0.01, ina liquid followed by adding the TiO₂ as obtained in step a.v. whilemaintaining the weight ratio of Mo to TiO₂ in the range of 0.05 to 0.15to form a mixture; c. stirring the mixture as obtained in step b. for aperiod in the range of 2 to 5 h, then filtering the mixture to form asolid material and then drying the solid material at a temperatureranging from 100 to 130° C. for a period in the range of 10 to 18 h; andd. calcining the material at a temperature in the range of 300 to 800°C. for a period in the range of 4 to 6 h in air to yield Mo—TiO₂nanocrystalline oxide catalyst.
 15. The process of claim 4, wherein thetemperature is in the range 650 to 800° C., the gas hourly spacevelocity (GHSV) is in the range of 10000 to 50000 ml g⁻¹ h¹, and thetime period is in the range 3 to 20 h.
 16. The process of claim 15,wherein the Mo supported TiO₂ catalyst comprises Mo in the range of 5 to15 wt % and TiO₂ in the range of 85 to 95 wt %, and the catalyst has aparticle size in the range of 80-150 nm.
 17. The process of claim 16,wherein the Mo supported TiO₂ catalyst is a nanocrystalline solid thathas been prepared according to the following process: a. preparing solidTiO₂ from a mixture of titanium isopropoxide Ti(i-Pr)₄ andoctadecyldimethyl (3-trimethoxy silylpropyl) ammonium chloride, presentin the ratio ranging from 50:3500:1 to 100:3500:1, in liquid, whereinthe mixture has been heated at a temperature in the range of 70 to 90°C. and then autoclaved at a temperature in the range of 150 to 200° C.to form a liquid containing solid material, wherein the solid materialis separated from the liquid and then calcined at a temperature in therange of 300 to 800° C. in air to yield the solid TiO₂; and b. mixingMoCl₃, cetyltrimethylammonium bromide and hydrazine, at a molar ratio ofMo:CTAB:hydrazine ranging from 1:1:0.01 to 1:2:0.01, in a liquidfollowed by adding the TiO₂, the weight ratio of Mo to TiO₂ being in therange of 0.05 to 0.15, to form a mixture comprising a solid materialthat is separated and then calcined at a temperature in the range of 300to 800° C. in air to yield the Mo—TiO₂ nanocrystalline catalyst
 18. Thecatalyst of claim 1, wherein the catalyst has been prepared according toa process comprising: a. preparing solid TiO₂ from a mixture of titaniumisopropoxide Ti(i-Pr)₄ and octadecyldimethyl (3-trimethoxy silylpropyl)ammonium chloride, present in the ratio ranging from 50:3500:1 to100:3500:1, in liquid, wherein the mixture has been heated at atemperature in the range of 70 to 90° C. and then autoclaved at atemperature in the range of 150 to 200° C. to form a liquid containingsolid material, wherein the solid material is separated from the liquidand then calcined at a temperature in the range of 300 to 800° C. in airto yield the solid TiO₂; and b. mixing MoCl₃, cetyltrimethylammoniumbromide and hydrazine, at a molar ratio of Mo:CTAB:hydrazine rangingfrom 1:1:0.01 to 1:2:0.01, in a liquid followed by adding the TiO₂, aweight ratio of Mo to TiO₂ in the range of 0.05 to 0.15, to form amixture comprising a solid material that is separated and then calcinedat a temperature in the range of 300 to 800° C. in air to yield theMo—TiO₂ nanocrystalline catalyst.
 19. The catalyst of claim 1, whereinthe catalyst comprises: a. TiO₂ prepared from a mixture of titaniumisopropoxide Ti(i-Pr)₄ and octadecyldimethyl (3-trimethoxy silylpropyl)ammonium chloride, present in the ratio ranging from 50:3500:1 to100:3500:1, wherein the TiO₂ has been calcined at a temperature in therange of 300 to 800° C. in air; and b. Mo support prepared from amixture of MoCl₃, cetyltrimethylammonium bromide and hydrazine, at amolar ratio of Mo:CTAB:hydrazine ranging from 1:1:0.01 to 1:2:0.01, andthe TiO₂, wherein the weight ratio of Mo to TiO₂ in the catalyst is inthe range of 0.05 to 0.15, and the catalyst has been calcined at atemperature in the range of 300 to 800° C. in air.
 20. The catalyst ofclaim 19, wherein the catalyst comprises: a. TiO₂ prepared from amixture of titanium isopropoxide Ti(i-Pr)₄ and octadecyldimethyl(3-trimethoxy silylpropyl) ammonium chloride, present in the ratioranging from 50:3500:1 to 100:3500:1, in liquid, wherein the mixture hasbeen heated at a temperature in the range of 70 to 90° C. and thenautoclaved at a temperature in the range of 150 to 200° C. to form aliquid containing solid material, wherein the solid material isseparated from the liquid and then calcined at a temperature in therange of 300 to 800° C. in air to yield the solid TiO₂; and b. the Mosupport has been prepared by from a mixture of MoCl₃,cetyltrimethylammonium bromide and hydrazine, at a molar ratio ofMo:CTAB:hydrazine ranging from 1:1:0.01 to 1:2:0.01, in a liquidfollowed by addition of the TiO₂ at a weight ratio of Mo to TiO₂ in therange of 0.05 to 0.15, to form a mixture comprising a solid materialthat is separated and then calcined at a temperature in the range of 300to 800° C. in air to yield the catalyst.